Without limiting generality, the present invention and its underlying technical objective are explained on the basis of high-pressure sensor elements, whereby one or multiple thin silicon chips, with or without an integrated evaluation circuit, are soldered onto a steel substrate having a steel diaphragm.
As is known from published German patent application document DE 10 2007 012 106 A1, the circuit and connection side of the silicon chips is situated on the side facing away from the steel diaphragm. A glass solder (also referred to below as “seal glass”), for example, is used as the solder. This technology is known, for example, as “pattern transfer.” However, there are various challenges with regard to processing. Multiple complex changes between front and back side processing of the chips are required. The handling of the small to very small chips used is complicated. Multiple complex changes between wafer processes, individual chip processes (soldering), and batch processes are necessary. Lastly, special measures are required in order to minimize cavity formation during soldering.
Published German patent application document DE 100 36 284 A1 describes a high-pressure sensor element in which at least one measuring element in the form of a strain gauge is mounted on a diaphragm, the measuring element being separated from the diaphragm by an electrically insulating layer. The measuring element is mounted on an electrically insulating substrate, which in a further step is fastened to the side of the diaphragm facing away from the measuring element, so that the electrically insulating substrate forms the electrically insulating layer.
Published German patent application document DE 10 2007 012 106 A1 discloses a pressure sensor having a metal housing and a semiconductor chip. The housing has a diaphragm formed in one piece with the housing, and an inlet for supplying a fluid to the diaphragm.
Published German patent application document DE 103 50 036 A1 and published German patent application document DE 10 2005 035 057 A1 each describe a method for manufacturing a semiconductor chip system, a plurality of semiconductor chips being connected to a carrier substrate via thin webs or support points on the back side. The webs are made of silicon, for example, and are surrounded by a cavity in the manufacturing process. Using an etching process which is selective for the carrier substrate and the semiconductor chips, the webs may be dissolved, thus separating the semiconductor chips from the carrier substrate.
Published German patent application document DE 199 34 114 A1 describes a substrate and a workpiece carrier for accommodating a plurality of such substrates for forming a composite substrate.